Here's my 2c, from the safety side.
I've done safety across for a ton manufacturing companies for the past 15 years. I used to do it via consulting first, helping out smaller firms (low fortune 500 to not even listed ) then got into large corporations and over the past 10 years, been exclusively at large corporations (fortune 30). I've worked with union and non-union with focus on safety.
There's good unions and bad unions for sure. But, what people need to understand is, there would be NO UNION activity at all if work conditions and/or employee satisfaction is being taken care of by management. Almost all manufacturing corps do VOE (voice of the employee) surveys now and do them very often; sometimes up to twice a year. The big driver behind that is to detect whether there is potential union activity and if there is, very proactive actions being done by management.
Some industries are more ripe for union activity due to it's historical nature and there will always be rumblings about forming a union in these environments. But due to the nature of union campaigns, you have to get the majority of workers to want to join a union; and that doesn't happen if, as i said, work conditions and/or employee satisfaction are being taken care of. Car manufacturing will always be ripe for union activity. ALWAYS. So if you know this going in, as the senior leadership, you gotta be proactive.
Somebody earlier posted something about TRIR (injury rate). The truth is, TRIR can be 'faked' because it is entirely self-adjudicated. OSHA provides the guidelines as to what is recordable and what's not, but the management team makes the judgement. I can assure you that many management team personnel try to fake the injury rate by trying to say an injury was only "first aid" vs being a recordable; or accuse the employee of the injury not happening at the workplace which also makes it not recordable. Now saying that, OSHA provides an anonymous forum for employees to complain about their workplace; and if they get a complaint, OSHA investigates. If OSHA does investigate, they will ask to see your injury logs and compare it to workers compensation to see if injuries are being recorded correctly.
Regardless, I will say that Tesla has steadily increased their internal safety department over the years. I know because i've been looking to apply for a senior level job there for a while!!!! They now have safety people even for their stores and service centers across the country, which is a good sign. Now, that may be very reactive v proactive actions; it could be that injuries have been occurring and they're reacting to that by investing in safety professionals. If that's the case, then it's no surprise if there's union activity because it means things got too out-of-control before acting. And if that's the case, then employees would need to see massive turnaround by management before trusting that management will take care of things without needing union intervention/representation.